摘要
表面等离子体共振(SPR)传感技术因其灵敏度高、无需标记、可原位实时监测的特点,被广泛应用在生物医学、化学检测、食品安全、环境监测等领域。对于波长调制型SPR传感器,由于光谱测量系统各部件对不同波长响应度不同,从而对光谱共振波长的实际位置产生干扰,影响到实验检测结果。为消除这种影响,提出了一种基于辐射度空间的SPR相对反射率校正方法,并使用阶数自适应拟合算法对共振波长进行精确测定。通过标定光谱测量系统的仪器响应曲线,将光谱仪得到的原始光谱转换成辐射光谱,进而计算出不依赖于光谱仪系统中任何部件的SPR相对反射率。相比于传统的反射率校正方式(以共振光谱除以非共振光谱的结果作为反射率光谱),此方法校正后的光谱在光谱形状上具备半峰宽更窄和共振峰更对称的优势,从而为精确确定共振波长提供了可靠的保障。随后基于拟合误差最小化的目标,对共振区域采用阶数自适应多项式拟合算法确定共振波长。实验测量了不同入射角度下的SPR共振光谱,使用此方法校正得到反射率光谱的半峰全宽保持在(100±10)nm,表明此方法的光谱峰形优势具备普适性;连续采集了4000组光谱并计算共振波长,其相对标准偏差为0.0078%,处理速度为每个光谱12 ms,表明此方法具备良好的抗噪声波动鲁棒性和光谱数据处理的实时性;测量了不同浓度下NaCl溶液的SPR共振光谱,其共振波长与溶液折射率线性相关系数为0.9985,品质因数为传统校正方式的3倍,表明此方法具备良好的可靠性,并且从光谱的处理算法层面提高了传感性能,相比于从工艺制备上提高品质因数的传统方式,处理简便,效果更突出。结果表明,基于辐射度空间的相对反射率矫正与阶数自适应拟合相结合的SPR共振波长检测方法具备可靠性好、运算速度快、分辨率高、抗噪声、品质因数高等特点,能够有效提高SPR传感器的数据处理与传感性能。
Surface Plasmon Resonance(SPR)sensing technology has been widely used in biomedical diagnosis,chemical detection,food safety,environmental monitoring and other fields due to its high sensitivity,in situ and label-free and real-time detection capability.For a wavelength interrogated SPR sensor,its resonance wavelength is measured for obtaining the analyte concentration.Because the optical spectrum analyzer(OSA)used in the SPR sensor has different photoelectric responses at different wavelengths,the measured resonance wavelength will deviate from the actual value in some extent,resulting in the measurement error.A radiation-based relative reflectance correction method is proposed in this work,which consists of the following three steps:(1)establishing the instrument response function(IRF)of the OSA used;(2)using the IRF to convert the reflected intensity spectrum of the SPR sensor directly measured with the OSA into the reflected power spectrum;(3)using the reflected power spectrum to determine the reflectance spectrum of the SPR sensor.The obtained reflectance spectrum is not affected by the SPR sensor system.Compared with the conventional reflectance correction method that needs to measure the resonance and non-resonance spectra of the SPR sensor,our method makes the resonance peak in the reflectance spectrum have a narrower FWHM and a more symmetrical shape and thus allows for more accurately determining the resonance wavelength.Based on the goal of minimizing the fitting error,an order-adaptive polynomial fitting algorithm is performed for the resonance region to determine the resonance wavelength.Experimentally,the SPR spectra at different incident angles are measured,and the FWHMs of the reflectance spectrum obtained by our method are maintained at(100±10)nm,indicating a universal shape advantage of this correction method.Then 4000 spectra are continuously collected,and their resonance wavelengths are calculated by the method,the results give a relative standard deviation of 0.0078%and a processing speed of 12 ms per spectrum.This indicates that the method has good robustness against noise fluctuations and real-time processing of spectral data.Lastly,the SPR resonance spectra of NaCl solutions at different concentrations are measured,it shows a linear correlation coefficient of 0.9985 between the resonance wavelength and refractive index of the solutions,and a Figure of Merit(FOM)two times higher than that of the conventional method.This indicates that the method has good reliability and improves the sensing performance from the level of the spectral processing algorithm.While the conventional method for improving FOM is from preparation technology,ours is easier to handle,and the effect is prominent.All the experimental results show that our SPR resonance wavelength determining the method that combines the radiation-based relative reflectance correction and the order-adaptive fitting algorithm has the characteristics of good reliability,fast calculation,high resolution,anti-noise and high FOM which can effectively improve the data processing and sensing performance of SPR sensor.
作者
尹涛
刘紫威
蔡宸
祁志美
YIN Tao;LIU Zi-wei;CAI Chen;QI Zhi-mei(State Key Laboratory of Transducer Technology,Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2021年第1期32-38,共7页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(61675203,61871365,61931018)
中国科学院科研仪器设备研制项目(YJKYYQ20180004)资助。
关键词
SPR传感
基于辐射度的光谱校正
自适应拟合
共振波长
SPR sensing
Radiation-based spectral correction
Self-adaptive fitting algorithm
Resonance wavelength determination
作者简介
尹涛,1994年生,中国科学院大学硕士研究生,e-mail:yintao17@mails.ucas.ac.cn;通讯作者:祁志美,e-mail:zhimei-qi@mail.ie.ac.cn。
